This invention relates to a storage system and, in particular, a technique of restoring stored data.
An information system of a corporation has a fear of shutting down abnormally due to a hardware breakdown, a bug in software, operational error on a user's part, or the like. Such cases are often accompanied by data error or a data breakdown. The data restoration technique is therefore important for corporation information systems.
For instance, a technique of restoring data using journal is disclosed in JP 2004-252686 A. According to this data restoration technique, a secondary volume is created as a copy of a primary volume, and update data written in the primary volume is stored in a journal volume.